A telecommunications network may support one or more messaging services. One example messaging service is the short message service, or SMS. SMS allows the communication of short text messages between mobile communications devices, such as mobile phones, personal digital assistants, and the like. For brevity, the term “mobile phone” is hereinafter used to generically refer to any type of mobile communications device, although the subject matter described herein is not so limited.
The delivery of an SMS message is a two-step process. First, if the receiver is a mobile subscriber, the receiver's current location—more specifically, the identity of the mobile switching center (MSC) that is currently serving the receiver's mobile phone, referred to as the serving MSC—must be determined. Second, the MT/SM message is forwarded to the serving MSC, which will transmit the MT/SM message to the receiver's mobile phone.
FIG. 1A is a block diagram illustrating processing of an MT/SM message in a conventional signaling system #7 (SS7) based telecommunications network according to the steps described above. Telecommunications network 100 includes a short messaging service center (SMSC) node 102 for processing SMS messages, such as MT/SM message 104, which was sent from a mobile subscriber, sender 106, and intended for another mobile subscriber, receiver 108. To determine the current location of receiver 108, SMSC 102 sends a send routing information for short message (SRI_SM) message 110 to the home location register (HLR) 112 which maintains the current location of receiver 108. HLR 112 sends a response message, such as SRI_SM_ACK message 114, to SMSC 102. SRI_SM_ACK message 114 includes information identifying subscriber 108, such as the (IMSI) for subscriber 108. In the conventional system illustrated in FIG. 1, the information identifying subscriber 108 is subscriber 108's IMSI number, represented in FIG. 1 as “IMSI#”. SRI_SM_ACK message 114 also includes information identifying the MSC currently serving receiver 108. In the conventional system illustrated in FIG. 1A, MSC 116 is currently serving receiver 108, and MSC 116 is identified by its network address, represented in FIG. 1 as “ADDR1”. SMSC 102 then issues a MT_FORWARD_SM message 118 to MSC 116, which delivers what is essentially the original MT/SM message 104′ to receiver 108.
In the scenario where sender 106 is in a first mobile telecommunications network and receiver 108 is in a second mobile telecommunications network, the SMS message is communicated from the first network, hereinafter referred to as the originating network, to the second network, hereinafter referred to as the terminating network. In the conventional network illustrated in FIG. 1A, SMSC 102 is an entity in the originating network and HLR 112 and MSC 116 are entities in a terminating network that is different from the originating network.
It is not uncommon for a terminating network to charge a termination fee for receiving and processing SMS messages that originate from other networks. The terminating network may determine the identity of the originating network—and thus determine whom to charge—by looking at the source address fields within either SRI_SM message 110 or MT_FORWARD_SM message 118. Moreover, both SRI_SM message 110 and MT_FORWARD_SM message 118 contain the address of SMSC 102 at two layers of the signaling message protocol, and thus within two separate sets of message parameters or fields: the signaling connection control part (SCCP) layer and the mobile application part (MAP) layer. Table 1, below, lists the parameter names for the two messages and the two layers.
TABLE 1SMSC Addresses Contained Within Signaling MessagesSMSC addressSMSC parameterOperationat SCCP layerat MAP layerSendRoutingInfoForSmCGPA GTAserviceCentreAddressMtForwardSmCGPA GTASM-RP-OA parameter
In the conventional telecommunication network illustrated in FIG. 1A, MSC 116 may, upon receiving MT_FORWARD_SM message 118, determine that the message originated from a different network and, in response to that determination, extract the SMSC address from MT_FORWARD_SM message 118. The terminating network may then identify the network to which SMSC 102 belongs and charge a termination fee 120 to the identified originating network.
To avoid being charged a termination fee for SMS messages sent to the terminating network, unscrupulous originating network operators may “spoof” (falsify) the contents of the SMS message so that the SMS message appears to have come from a third telecommunications network rather than from the actual originating network.
FIG. 1B is a block diagram illustrating MT/SM spoofing in the conventional telecommunications network of FIG. 1A. Elements of FIG. 1B are essentially identical to their like-numbered counterparts in FIG. 1A, and therefore their descriptions will not be repeated here. In addition to the originating and terminating networks of FIG. 1A, now labeled as “NW1” and “NW2”, respectively, FIG. 1B also includes a third network, “NW3”, which contains its own SMSC 122. In the scenario illustrated in FIG. 1B, terminating network NW2 receives from originating network NW1 an SMS message, such as MT_FORWARD_SM message 118′, with a spoofed origination address (“ADDR3”) that falsely indicates that the SMS message came from SMSC 122. The terminating network then incorrectly charges termination fee 120′ to the third telecommunications network NW3 rather than to the actual originating network NW1. In this manner, an unscrupulous network operator (e.g., the operator of NW1) may fraudulently avoid termination fees that would otherwise be imposed upon it by the terminating network NW2.
This is a particularly pernicious problem in light of unwanted solicitations, colloquially called “spam”, which flood the world's email systems daily with millions or billions of unwanted messages. The entities that generate these unwanted communications have recently started sending spam via SMS. Spam SMS messages are particularly grievous since the subscriber is often charged a fee for every SMS message received, which results in a subscriber not only receiving unwanted and often offensive SMS messages, but the subscriber having to pay for these unwanted SMS messages. Some subscribers may have plans that have a finite number of SMS messages that may be sent or received within a billing period, where the subscriber is charged a steep fee for every additional message sent or received during that billing period. In a worst case scenario, the charge levied upon the subscriber due to the additional SMS messages may be many times more than the cost of the original subscription. Network operators may then face the prospect of absorbing the cost themselves or risk losing subscribers. In this scenario particularly, the network operator would desire to detect and discard spoofed MT/SM messages.
Accordingly, in light of the potential for fraudulent spoofing of SMS addresses, there exists a need for systems, methods, and computer readable media for detecting and mitigating address spoofing in messaging service transactions.